Carburetor



y 1937- J. w. FITZGERALD 2,080,258

CARBURETOR Filed July 13, 1935 3 Sheets-Sheefl QMWKW Jafiv IKE/255mb T May 11, 1937- J. w. FITZ GERALD.

CARBURETOR 3 Sheets-Sheet 2 Filed July 13, 1935 May 11, 1937.

J. W. FITZ GERALD CARBURETOR Filed July 13, 1935 3 Sheets-Sheet 3 Patented May 11, 1937 UNITED STATES PATENT OFFICE CARBURETOB Application July 13, 1935, Serial No. 31,245

18 Claims. (01, 123-119) This invention relates to improvements in carburetors and refers more particularly to means for automatically controlling the choke valve of a carburetor.

It is an object of this invention to provide a choke control whereby the choke valve is automatically closed upon opening of the throttle valve to a starting position and is opened a degree determinate upon the thermal conditions of the engine upon the starting of the engine.

Another object of this invention resides in the provision of means for controlling the functioning of an automatic choke control by the flow of electric current incidental to the'starting" of the engine. I

A further object of this invention is to provide a choke control of the character described wherein an electro-responsive element serves sive latch likewisegoverning the connection between the choke valve and its actuator.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, conibination and arrangement of parts substantiallyas hereinafter described and more particularly defined by the appended claims, it being understood. that suchchanges in the precise embodiment of the hereindisclosed invention may be made asf com e within the scope of the claims. The accompanying drawings illustrate one complete example of the physical embodiment of the invention constructed according to the best mode so far devised for the practical application of the principlesthereof, and in which:

Figure 1 is a side view of a carburetor showing the application of this invention 'thereto,- parts of the mechanism being shown in section;

Figure 2 is an enlarged side view of the carburetor and the choke control mechanism. with the parts in a position other than that shown in Figure'l; j 1 Figure 3 is a detail section view taken through, "I Figu're 2 on the plane of the line 3-.--3; and v Figure 4 is aview similar to Figure 2 but showing the parts'instill another position of adjustment. I L

Referring now more particularly to the accompanying drawings in which like numerals indicate like parts throughout 'theseveral views-,- the numeral 5 designates a I carburetor having a mixing chamber t connectible with the manifold 10f an internal combustion engine, an air inlet "8, and a float chamber 9. Fuel is conducted to the float chamber through a line It in the conventional manner and the fuel-air mixture passes into the manifold 1 as determined by theadjustmentof a throttle valve I I. The admission of air '5 is controlled by a choke valve l2 which, like the throttle valve: is of the conventional butterfly type.

The throttle valve'is actuated from an acce erator (not shown) by means of a link l3 connected to an arm I 4 flxedto the shaft ii of the throttle valve. Also flxedtothe shaft is a lever l6 which is connected with the short arm l1 of a bell crank lever l8 pivoted as at I 9 to the body of the carburetor, through a separable connection indicated generally by the numeral 20. The long arm 2| of the bell crank lever I8 is "connected through a link 22 witha lever 23 fixed to the shaft 24 of the choke valve l2. A torsion spring 25 yieldingly maintains the choke valve open.

The separable connection comprises .two rods 26 and 21 connected respectively tothelevers l6 and I1'. Secured to the rod 28 is a solenoid 28 having a hollow core in which the outer end 29 of the rod 21 is slidably disposed. The rod 21 is reduced in diameter as at 30 to provide a shoulder 3| with which a latch 32 engages tohold the rods 26 and 21 against separation. ,The latch 32 is in the form of an a ariy bent strip mounted at 30 its upper end. by a spring strip 33 secured tothe core of the electromagnet in such position that its lower arm 34 moves across the lower end of the solenoid. v l

This lower horizontal arm 34 has a keyhole 35 slot 35 in which the reduced portion 30 of the rod 21 is disposed. With the latch 32 in its normal position shown in Figure 1, the small end of the keyhole slot 35 is engaged with therod 21 so that the arm 34 is disposed under the shoulder 3| tohold the rods 26 and 21 connected. Upon energization of the solenoid 28 the latch 32 being of magnetic metal moves to align the large end of the keyhole slot with the rod 21 thus releasing -.separable connection 20 together is released to 'permit opening of the choke, valve l2 regardless oi the position of the throttle valve ll.

However, the degree of opening of the choke valve I2 is controlled by a thermal latch indicated generally by the numeral 36. This latch comprises a stepped flange 31 fixed on the rod 2'! and a bimetallic finger 38 fixed to the solenoid in thermal relationship thereto to be influenced thermally by the solenoid. As the temperature at the bimetallic strip orfinger 38 rises, its lower end which engages the stepped flange 31 moves outwardly to allow astep by step variation in the relative positions of the choke valve and throttle valve until the bimetallic finger moves outwardly sufiiciently far to entirely disengage the flange 31 whereupon the choke valve l2 moves to its fully open position and remains there regardless of variations in the position of the throttle valve. To produce the heat necessary to influence the bimetallic holding finger 38, the solenoid 28 is preferably wound with resistance wire.

Operation the choke valve by reason of the connection 20 to its fully closed position against the action oi! its spring 25. As the engine startsand sufficient current is generatedby its generator, the

solenoid becomes energized and attracts the latch 32 to'release the rod g! for movement away from the rod 26.

However, inasmuch as the thermal latch 36 is v in position engaging the lowermost step on the flange 31, the choke valve remains in its closed position.

'As the engine begins to operate normally and the temperature at the thermal latch 36 rises, the choke valve is gradually permitted to open, assuming that the throttle valve remains in its position shown. In this condition of the engine that is, before it is warmed up to its normal running temperature, if the throttle is suddenly advanced unless some means of enriching the fuelremains connected with the throttlevalve to be closed or at least moved toward closed position upon opening of the throttle valve. At the end of this period of time, the thermal latch 36 moves to its position in Figure 4 to entirely disengage the fiange 31 and permit the choke valve to .move to its fully open position and to 'remain there regardless of subsequent adjustment of the throttle va'lve.

Obviously, upon stopping of the engine the connection 20 will be re-established automatically by the closing of the throttle valve which lowers the latch to its position at which-it engages under the shoulder 3|.

From the foregoing description taken in connection with the accompanying drawings, it will be readily apparent to those skilled in the art to which this invention appertains, that this invention' provides a novel and simple manner of automatically controlling the position of the choke valve in a carburetor and coordinating its functioning with the adjustment of the throttle valve during the starting cycle of the engine.

What I claim as my invention is:

1. In a carburetor, the combination 01' a choke valve biased to open position, a manually controlled throttle valve, a connection between the throttle valve and choke valve for translating an opening movement of the throttle valve into a closing movement of the choke valve, said connection being separable to free the valves from each other, and automatically operable means for breaking the connection between the valves.

2. In a carburetor, the combination of a choke valve biased to open position, a manually controlled throttle valve, a connection between the valves whereby movement of the throttle valve toward open position moves the choke valve toward closed position, electro-responsive means for breaking the connection between the valves, and thermally responsive means for delaying complete breakage of the connection between the valves.

3. In a carburetor, the combination of a choke valve biased to open position, a manually con- .trolled throttle valve, a multiple connection between the valves whereby movement of the throttle valve toward open position moves the choke valve toward closed position, electro-responsive means for breaking one of said connections, and

thermally resp nsive means for controlling the other connection whereby complete breakage of the connection between the valves requires a predetermined temperature rise at said thermal means.

4. In a carburetor, the combination of a choke valve biased to open position, a'throttle valve, and a connection between the valves whereby the valves are held in definite relative positions and whereby motion of one valve is positively translated into corresponding motion of the other valve, said connection being adjustable as to length in accordance with temperature changes thereat.

5. In a carburetor, the combination of a choke valve biased to open position, a throttle valve, means for adjusting the throttle valve, and a thermally controlled connection between the valves operable to maintain the valves connected in different relative positions so that movement of the throttle valve toward open position moves the choke valve toward closed position different degrees until a predetermined temperature is attained at said thermal means whereupon the connection between the valves is entirely disrupted.

6. In a carburetor, the combination of a choke valve biased to open position, a throttle valve, means for opening and closing the throttle valve, a connection between the valves comprising a part movable with the throttle valve, another part movable with the choke valve, a thermal latch carried by one part, and a stepped abutment carried by the other part and with which the thermal latch engages to maintain the valves connected in different relative positions depend-. ent upon the temperature at said thermal latch.

'7. In a carburetor, the combination of a choke valve biased to open position, a throttle valve, means for opening and closing the throttle valve,

a connection between the valves comprising apart movable with the throttle valve, another part movable with the choke valve, a mechanical latch connecting said parts to maintain a fixed relative relationship between the valves, means for releasing said mechanical latch to allow sepa-' ration of said parts,- and means coordinated with the temperature rise in an engine with which the carburetor is used for controlling the rate of separation of said parts.

8. In a carburetor, the combination of a choke valve biased to open position, a throttle valve, means to open and close the throttle valve, a connection between the valves comprising a part movable with the throttle valve, a part movable with the choke valve, a mechanical latch carried by one part and engageable with an abutment on the other part to hold the valves in definite fixed relative positions with respect to each other,

electro-responsive means for disabling the me-v chanical latch, and a thermal latch operable to hold the valves in dilferent predetermined relative positions with respect to each other and to completely disconnect the valves from each other upon a predetermined temperature rise at said thermal latch.

9. In a carburetor, the combination of a choke valve biased to open position, a throttle valve,

"means to open and close the throttle valve, a

connection between the valves comprising two latches, and means for quickly releasing one latch and for slowly'releasing the other latch.

10. In a carburetor, the combination of a choke valve biased to open position, a throttle valve, means for opening and closing the throttle valve, means for connecting the valves so that movement of the throttle valve toward open position eifects movement of the choke valve towards closed position, said connection comprising rapidly acting and slowly acting latches, and means controlled by some function of .an engine with which the carburetor is used'for releasing said latches.

11. In a carburetor for internal combustion engines having an electrical system including a generator, the combination of a choke valve "biased to open position, a throttle valve, means for adjusting the throttle valve, a connection between the valves so that movement of the throttle valve toward open position moves the choke valve toward closed position, said connection comprising quick acting and slow acting latches,

' and common electro-responsive means energized ical latch, and thermally responsive means providing an auxiliary latch and operable to hold the valves connected at difierent relative positions with respect to each other until a predetermined temperature rise has been attained at said thermal means.

13.11: a carburetor for internal combustion engines having an electrical system including a generator adapted to generate current during normal operation oi the engine, the combination of a choke valve biased to open position,

a throttle valve, means for adjusting the throttle valve, a separable connection between the valves whereby movement of the'throttle valve toward open position moves the choke valve toward closed position, said connection comprising a mechanical latch adapted to hold the valves in fixed relative positions, electro-responsive means energized from the generator for releasing the mechanical latch and a thermal latch augment,

ing the mechanical latch and adapted to gradually permit disconnection of the choke valve from the throttle valve in step with the temperature rise at said thermal latch.

valves whereby movement of the throttle valve toward open position moves the choke valve toward closed position, electro-responsive means for breaking the connection between the valves, and thermally responsive means to change the length of the connection between the valves and thereby their degree of opening.

15. In a carburetor for internal combustion engines, the combination of a choke valve, a throttle valve, a two-part link including a connecting latch engageable 'when the throttle valve is completely closed to connect the valves, magnetic means operable by the running of the engine to prevent engagement of the latch if the engine is running and. to disengage said latch upon starting of the engine, and a second connecting latch responsive to ambient thermal conditions to permit gradual lengthening of the link. 16. In a carburetor, the combination of a choke valve biased to open position, a throttle valve,

'means for opening and closing the throttle valve,

means for connecting the valves so that movement of the throttle valve toward open position effects movement of the choke valve towards closed position, said connection comprising rapidly acting latch and slowly acting length adjusting devices, and means controlled by some func tion of an engine with which the carburetor is used for successively releasing said rapidly acting latch and the slowly acting length adjusting devices.

17. In a carburetor for internal combustion engines having an electrical system including a generator, the combination of a choke valve biased to open position, a throttle valve, means for adjusting the throttle valve, a connection between the valves so that movement of the throttle valve toward open position moves the choke valve tow'ard closed position, said connection comprising rapidly acting latch and slowly acting length adjusting devices, and means controlled by some function of the engine for successively releasing the rapidly acting latch and the slowly acting length adjusting devices.

18. In a carburetor for internal combustion engines, the combination of a choke valve biased to open position, a throttle valve, a connection adjustable as to length between said valves for holding them in definite relative positions, and means for predetermining the length of said connection, said means being responsive to and JOHN w. FITZ GERALD. 

